In the conventional type of concrete parking curbs (i.e., slender forms of semi-trapezoidal cross-section), reinforcing bars may be provided at the top and bottom. The bottom reinforcing bar is initially supported within the casting form for the curb by suitable means so as to hold the bar in position and the top bar is hand placed after pouring of the concrete into the form. Centering of the bars is accomplished by eye and usually is inaccurate by virtue of the lack of lateral restraint. Additionally, it is very difficult to place the top bar accurately at a given position in the concrete.
Some supports are known for supporting reinforcing bars in spaced positions. These include such supports as disclosed in U.S. Pat. Nos. 1,268,887; 1,880,710; 3,530,634; and 3,694,989 as well as in British Pat. No. 904,766. These known structures are believed to be less suitable for withstanding the weight of reinforcing bars then is desirable for the purpose.